Depilatory agent



Patented Oct. 22, 1935 UNITED STATES PATENT OFFICE DEPILATORY AGENT land No Drawing. Application April 20, 1933, Serial No. 667,056. In New Zealand May 13, 1932 Claims.

This invention relates to improvements in the removal of hair and/or wool from hides, pelts or skins.

The usual depilatory agent commercially used 5 at the present time in the removing of hair and/or wool from hides, pelts, skins or the like, comprises sodium sulphide and lime. Notwithstanding the fact that this preparation has obvious disadvantages its comparatively low cost and the absence of any commercially more successful preparation has resulted in its comparatively general use. The disadvantages of this preparation almost entirely arise from the use of lime which is necessary to maintain the requisite degree of alkalinity during the process. The use of lime, however, is injurious not only to the skin but also the hair in that the reactions taking place between the sodium sulphide water and lime form inter alia insoluble calcium compounds while further the surface tension of the liquid is high causing the area attacked by the liquid to spread up the hair by capillary attraction, the greater the surface tension of the liquid the greater being the amount of capillary attraction. The result, therefore, is that the skin is toughened and hair damaged and very considerable treatment as by sulphuric acid baths is necessary to minimize the damaging effect of the lime.

3o Apart from this aspect the lime in combination with the sodium sulphide must be mixed with hot Water to obtain really satisfactory results,

while the resultant preparation is of a caustic nature and is very apt to injure the hands of 35 the workers.

From the chemical standpoint the essential depilatory agent in the aforesaid preparation is the sodium sulphide which attacks the keratin of the hair, laying it open to the attack of the alkali 40 produced inter alia by the lime. This hydrolysis of the keratin following upon the attack by the sulphide, readily removes the hair from the pelt. When sodium sulphide is mixed with water the following chemical reactions occur:

NazS (sodium sulphide) +H2O (water) NaI-IS (sodium hydrosulphide) NaOH (sodium hydroxide) alkalinity as the original sodium hydroxide is used up in the attack or lost from other causes.

Now as the result of my many experiments and investigations as to the requisites of a satisfactory depilatory for use in the process of the present invention, I have found that the essential characteristics thereof are as follows:-

1. The preparation must not be expensive and must be capable of commercial use in bulk.

2. The surface tension of the depilatory agent 10 must be low so that so far as is possible such agent will only attack the roots of the hairs and their immediate environments and prevent the removal of the top tissues so essential to obtain what is known as a perfect bloom and prevent 15 scale being lifted off with the wool.

3. That the deposits on the skin pelt and hair should be so far as is possible of soluble salts and compounds so that they can be easily removed without having to subject the skins and/or hair 20 to injurious and drastic treatment to remove same.

I have found that it is possible to dispense with the objectionable lime.

According to the process of this invention, 5 hair and/or wool is removed from hides, pelts or skins by employing a depilatory as a paint on the flesh side thereof, said paint comprising a sodium sulphide base and a soap whereby a uniform degree of alkalinity and low surface tension is maintained, and the area of attack localized to the hair roots.

The addition of a sufiicient proportion of a soap to the sodium sulphide enables the resultant preparation to attain the necessary efficiency while any deposits on the skin and/ or hair are soluble salts of sodium which are: readily scoured out. Furthermore by the use of a soap preferably with addition of oil and. naphthalene or the like and a glutinous thickening agent all herein- 40 after referred to we have found that the prep-aration may be prepared cold and is not injurious to the operators hands, brushes, clothes, etc.

Although I find that a satisfactory depilatory agent for use in the process of this invention can be made by the combination of sodium sulphide Water and a soap or its equivalent I find in practice that the best results are obtained by the addition of a suitable oil such as neats-foot oil and also naphthalene. It will also be obvious of course that a thickening agent is necessary to thicken the preparation to a degree of consistency as will enable it to be most satisfactorily painted on the skins.

Without, therefore, in any Way limiting the I neats-foot oil.

Preferably about 50.154 grains of naphthalene.

7 ounces avoirdupois (about) of pollard or other convenient thickening agent.

Preferably the sodium sulphide is ground to a powder and stirred into the cold water the soap then slowly added, stirring all the while, the oil and naphthalene then stirred in and finally the thickening agent to which a portion of the original water has been added to make a consistent paste, is added until the preparation is of the consistency of a thick emulsion. I 'The preparation may be painted on the skins in the usual way, the quantity varying with the nature of the skins to be treated.

After the removal of the Wool the pelts are thrown into strong lime liquor in vats and paddled for 24 hours. The pelts are then stacked in heaps for seven days and are fleshed and pickled in the usual manner. 7

Having thus described my invention, what I claim is:

1. A depilatory for application to the flesh side of hides as a paint and consisting of 'a sodium sulphide base, a thickening agent, and a soap.

2. A depilatory for application to the flesh side of hides as a paint and consisting of a sodium sulphide base, a thickening agent, a soap, and an oil.

3. A depilatory for application to the flesh side of hides as a paint and consisting of a sodium sulphide base, a thickening agent, a soap, and naphthalene.

4. A depilatory' for application to the flesh side 7 of hides as a paint and consisting of a sodium sulphide base, a thickening agent, a soap, an oil, and naphthalene.

5; A depilatory for application to the flesh side of hides as a paint and consisting of a sodium sulphide base, a thickening agent, and a soap in the approximate proportions by weight of 30, 4 and 7 respectively.

OONAH MARGARET HEDBERG. 

